Ruthenium Carbonyl-Catalyzed [2 + 2 + 1]- Cycloaddition of Ketones, Olefins, and Carbon Monoxide, Leading to Functionalized γ-Butyrolactones

Ruthenium-Catalyzed Transfer Hydrogenation for C–C Bond Formation: Hydrohydroxyalkylation and Hydroaminoalkylation via Reactant Redox Pairs

“…A mononuclear ruthenium(0) complex 71 promotes alkyne-dione oxidative coupling to form the indicated oxaruthenacycle. 72,73 Direct protonation of the oxaruthenacycle by the diol or ketol is postulated to be slow compared to protonolytic cleavage of the oxaruthenacycle by the carboxylic acid. The resulting ruthenium carboxylate exchanges with the diol or ketol to form a ruthenium alkoxide, which upon β-hydride elimination releases the ketol or dione, respectively, and a vinylruthenium hydride.…”

The Ru3(CO)12-Catalyzed Intermolecular [2 + 2 + 1] Cyclocoupling of Imines, Alkenes or Alkynes, and Carbon Monoxide: A New Synthesis of Functionalized γ-Lactams

“…We initially examined the reaction of an imine which contained a 2-pyridyl group, since it has been reported that such a group, when adjacent to a carbonyl group has an accelerating effect in the ketone cycloadditions. 7 We were pleased to observe that the reaction proceeded smoothly and efficiently. The reaction of imine 1a (1 mmol) with ethylene (3 atmospheres) at 5 atmospheres of CO in toluene (3 mL) in the presence of Ru 3 (CO) 12 (0.025 mmol) at 160°C for 20 hours furnished the expected g-lactam 2a in 97% isolated yield, based on 1a (eq 1).…”

“…Quite recently, we reported the first example of the intermolecular [2+2+1] cyclocoupling of ketones, ole-fins, and CO catalyzed by Ru 3 (CO) 12 , a reaction which leads to the formation of g-butyrolactones bearing carbonyl or N-heterocyclic groups at the g-position. 7 This finding prompted us to examine the possibility of using imines in place of ketones for the synthesis of g-lactams, which are of importance for use as pharmaceutical agents. 8 Herein, we wish to report that the intermolecular [2+2+1] cyclocoupling of imines, alkene or alkynes, and CO can be achieved catalytically, using Ru 3 (CO) 12 as the catalyst.…”

Ruthenium-Catalyzed Transfer Hydrogenation for C–C Bond Formation: Hydrohydroxyalkylation and Hydroaminoalkylation via Reactant Redox Pairs

“…A mononuclear ruthenium(0) complex 71 promotes alkyne-dione oxidative coupling to form the indicated oxaruthenacycle. 72,73 Direct protonation of the oxaruthenacycle by the diol or ketol is postulated to be slow compared to protonolytic cleavage of the oxaruthenacycle by the carboxylic acid. The resulting ruthenium carboxylate exchanges with the diol or ketol to form a ruthenium alkoxide, which upon β-hydride elimination releases the ketol or dione, respectively, and a vinylruthenium hydride.…”